Sleep apnea is a sleep disorder commonly characterized by pauses in breathing during sleep. These episodes, called apneas, each last long enough so one or more breaths are missed, and occur repeatedly throughout sleep. The standard definition of any apneic event includes a minimum ten second interval between breaths, with either a neurological arousal (three-second or greater shift in EEG frequency, measured at C3, C4, O1, or O2), or a blood oxygen desaturation of three-four percent or greater, or both arousal and desaturation. Sleep apnea is diagnosed with an overnight sleep test called a polysomnogram.
Often, the individual with sleep apnea is unaware of having difficulty breathing, even upon awakening. Sleep apnea is recognized as a problem by others witnessing the individual during episodes or is suspected because of its effects on the body. Symptoms may be present for years, even decades without identification, during which time the sufferer may become conditioned to the daytime sleepiness and fatigue associated with significant levels of sleep disturbance.
Fortunately, sleep apnea is treatable. Some treatments involve lifestyle changes, such as avoiding alcohol and medications that relax the central nervous system (for example, sedatives and muscle relaxants), losing weight, and quitting smoking. Some people are helped by special pillows or devices that keep them from sleeping on their backs, or oral appliances to keep the airway open during sleep. If these methods are inadequate, doctors often recommend continuous positive airway pressure (CPAP) therapy, in which a face mask is attached to a tube and a machine that blows pressurized air into the mask and through the airway to keep it open. (See Wikipedia: Sleep Apena, available at—http://en.wikipedia.org/wiki/Sleep_apnea).
Since sleep apnea occurs when a person is sleeping, devices and therapies used to treat sleep apnea should generally be designed so as not to significantly interfere with a person's sleep.
Devices that prevent a person from rolling over may interfere with sleep to a lesser extent, insomuch as they prevent a person from sleeping in a certain position. CPAP devices, on the other hand, while moderately quiet, do blow a continuous stream of forced air into a patient's mouth/nose. Further, the patient also exhales, and there is cyclic noise from the patient's natural breathing. While people may not typically snore or breathe loudly enough to wake themselves up, CPAP devices have tubing included therein which can resonate and amplify sound, and some of the tubing may even run near a patient's ear or ears, thus delivering the sound directly past the source of hearing. CPAP devices may also generate noise from operation of the motor of the flow generator, the sound of the air moving through the tubing and/or mask, and the noise of air leaving various vents in the mask or tubing. All of these factors (e.g., conducted noise as well as radiated noise) can contribute to noise in the CPAP system that may adversely affect patient and/or bed partner comfort, depending on both the magnitude and character of the noise. Moreover, excessive noise can lead to patients being non-compliant with CPAP therapy.
There is a long felt and continuing need to reduce the noise associated with CPAP therapy. Reducing the noise associated with CPAP therapy can significantly improve the user friendliness and compliance of CPAP treatment.